Differential drum for mine anchors



Feb. 10, 1948. J. B. GL NNON 2,435,580

DIFFERENTIAL DRUM FOR MINE ANCHORS Filed Sept. 27, 1952 Eaten/02":

Jamesfl; Glen/now W a Z M Patented Feb. 10, 1948 UNITED STATES PATENT OFFICE DIFFERENTIAL DRUM FOR MINE ANCHORS James B. Glennon, United States Navy Application September 2'7, 1932, Serial N0.635,117'

(Granted under the act of March 3, 1883, as

amendedApril 30, 1928; 370 0. G. 757) 9 Claims.

1. This invention relates to a drum for mine anchors so constructed that the mine anchor cable is paid out at different rates and has for its object to provide a means that will cause the mine case toseparate from its anchor at different speeds during various stages of. the unwinding of theanchorcable.

With the above and other objects in view, the invention consists in the construction, combination and arrangement of parts as will be described more fully hereinafter.

The drawing shows one embodiment of my invention.

In mine assemblies designed to go to the bottom before the mooring cable drum is locked, it is necessary to have several major. changes in the rate at which the mine case separates from the mine anchor. At first'ithe mine case and the anchor must separate rapidly until asfew feet apart, thus avoiding damage to. the mine case when the anchor strikes ahardbottom, as well as avoiding immersion of the mine case in a soft muddy bottom.. Nextrthe mine and anchor must separate slowly so thatthereis no possibility that the mine will return. and damage the mine lay-er (especially a submarine mine layer) during a shallow water plant. Then the mine must finally ascendto'its proper level in a brief period even where depths are. great,for during this interval the mine is exposed to sweeping, operations but is too deep to be efiective against an enemy vessel. The force acting on the mooring. cable drum consists ofthe pull of the: anchor cable, due in general to the buoyancy of the mine case,. and the retarding force caused by the action of the brake provided to control. the rate of unwinding of the cable; Assuming that both these forces remain constant, the rate of turning of the drum will be proportional to thelever arm of the pull of the mooring cable, i. e., to the radius of the cylinder upon which the cable is wound, which may be either the drum itself or a cylinder built up by layers of" the mooring cable itself on the drum. Further, the rate of separation. of the case from the anchor per turn of the drum will also.be proportionalt'o the same-radius since this fixes the length ofcable. unwound by eachturn ofv the drum. Therefore, the rate of separation of the case from the anchor will. vary directly as the square of the radius ofthe cylinder onwhich the cable, is. wound. This is the principle upon which the functioning of my invention depends. The drum, which'is suitably mounted in frame members I, comprises three sections; a section 2 of relatively large diameter, a section 3 of small diameter anda section 40f diameter intermediate those of the cthertwo sections. In winding the cable 8 on the drum the major part thereof is placed on section 4, then the cable is engaged in aslot in disk 5 to prevent its slipping and'the desired length wound on section 3, the cable is engaged in a slot in flange 6 on section 2 and twoorthree turns placed on section 2. The end of the cable is then passed under guide 1 and up through the fairlead to the'eye 1" onthelower portion of the mine M- to which the end is attached.

Asthe case begins to separate from the anchor, the cable will first unwind from section '2 which, being of large diameter, will pay out the cable rapidly and will permit the case to separate from the'anchor before the anchor strikes bottom.

While the cable is unwinding from section 3 thecase and anchor will separate slowly, due to the small radius of that part of the drum; The time consumed in unwinding this portion may easily be made five to tenminutes, thusthere will be no likelihood of the mine rising rapidly enough to contact the mine layer.

'Thereafter, the mine laying vessel having had sufficient time to move out of danger from the mine, the remainder of the cable willbe released fromithe part 4 ofthe drum with relative rapidity and the mine will quickly reach its final position.

The rate at which the cable runs out is controlled by the brake mechanism comprising a rotatable paddle wheel llconnected through the power reducing gearing train Hi to gear wheel H on the drum. A protective housing I2 is disposed around wheel 9 to prevent fouling of the wheel, itbeingunderstood that water has ready ingress to and egress from the housing. A fixed paddle wheel i3 is mounted in housing l2 to prevent free circulation of the water therein and to set upturbulences in the water to increase the braking effect of the paddle wheel 9. It is=apparentthat when a mine connected to its anchor by a cable wound on a drum as herein shown. is launched, thellarge radius of the part 2 of the: drum will afford a long lever arm and so the-pull of the mine on the cable will rotate paddle wheelv 9' at a relatively high rate and due to the length of cable unwound from part 2 at each revolution, the mine and anchor will rapidly separateof part 3 of the drum, together. with the. short:

The power afiorded by the small radius is then unwound at a rate intermediate the two The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

I claim:

1. A differential drum for mine anchors, comprising a rotatably mounted member .having a portion of relatively large radius to carry a small number of turns of cable, a portion of small radius adjacent thereto to carry a moderate number of turns of cable, a portion of radius intermediate the radii of the two above mentioned portions to carry the major portion of the cable, a guide around which the cable may run, a housing, a fixed paddle wheel in said housing, a rotatable paddle wheel in said housing, and a gear train connecting said rotatable Wheel with said rotatably mounted member.

2. A differential drum for mine anchors, comprising a rotatably mounted member having a portion of relatively large radius to carry a small number of turns of cable, a portion of small radius adjacent thereto to carry a moderate number of turns of cable, a portion of radius intermediate the radii of the two above mentioned portions to carry the major portion of the cable, a guide around which the cable may run, and means connected to said rotatably mounted member adapted to act upon water in which said drum is immersed to exert a braking effect upon said rotatably mounted member.

3. A differential drum for mine anchors, comprising a rotatably mounted member having a portion of relatively large radius to carry a small number of turns of cable, a portion of small radius adjacent thereto to carry a moderate number of turns of cable, a portion of radius intermediate the radii of the two above mentioned portion to carry the major portion of the cable, a guide around which the cable may run, and means to retard the rotation of said rotatably mounted member.

4. A differential drum for mine anchors, comprising a rotatably mounted member having a portion of relatively large radius, a portion of intermediate radius, and a portion of relatively small radius disposed between the aforesaid two portions, and means adapted to act upon water in which said drum is immersed to effect a braking action on the said rotatably mounted member.

5. A differential drum for mine anchors, comprising a rotatably mounted member having a portion of relatively large radius, a portion of intermediate radius, and a portion of relatively small radius .disposed between the aforesaid two portions, and means to retard the rotation of said rotatably mounted member.

6. A differential drum for mine anchors, com- 1 prising a rotatably mounted member adapted to hav wound on it the anchor cable, the said memand means including a rotatable paddle wheel driven by said first mentioned means and a fixed paddle wheel adjacent thereto acting upon the waterinwhich the mine is being planted to retard the paying out of the cable.

8. A device of the character disclosed for mooring a buoyant mine within a body of water comprising a mine anchor, a rotatable drum arranged within said mine anchor adapted to unwind a length of cable therefrom, a buoyant mine secured to said cable, a device operatively connected to said drum adapted to act upon the water for retarding the rotation of the drum variably in response to changes in the turning moment applied thereto by said buoyant mine when the device has been launched Within the body of water, means for causing a first length of cable to be paid out from the mine anchor at a relatively fast rate, means for causing a succeeding length of the cable to be paid out from the mine anchor at a relatively slow rate, and means for causing the remainder of the cable to be paid out from the mine anchor at an intermediate rate, all of said means being arranged on said rotatable drum.

9. In a mine assembly comprising a mine anchor having a buoyant min normally resting thereon, a mooring cable having one end thereof secured to the mine and the major portion of the cable arranged within said mine anchor, means for paying out said cable from the mine anchor as the mine and anchor are launched within a body of water, means arranged within the mine anchor for causing the mine to be separated from the anchor at a relatively high rate until a predetermined length of cable has been paid out from the mine anchor, mean controlled by the cable for causing the mine to separate from the anchor at a considerably slower rate until a predetermined additional length of cable has been paid out from the mine anchor, and means controlled by the cable for causing the mine to be separated from the mine anchor at an intermediate rate while the remaining cable is being paid out from the mine anchor.

'- JAMES B. GLENNON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Doose Nov, 22, 1932 

